It is important for public-safety responders to be able to communicate with each other on a regular basis. As a result, one of the most commonly used tools in the public-safety context is a wireless-communication device (WCD)—referred to in this disclosure as a “mobile radio.” Examples of commonly used mobile radios include cell phones, smartphones, tablets, notebook computers, laptop computers, and the like, and further examples include a handheld transceiver, often referred to by terms such as walkie-talkie, two-way radio, and the like. Some mobile radios include the functionality of, e.g., both a smartphone and a two-way radio. And certainly many other examples of mobile radios could be listed as well, as known to those having skill in the relevant art.
Mobile radios are generally configured with the ability to communicate with other network entities via a wireless network. Well known examples of wireless-communication protocols according to which such wireless networks operate include relatively long-range wireless-communication protocols (e.g., Global System for Mobile Communications (GSM), Long Term Evolution (LTE), and the like), relatively short-range wireless-communication protocols (e.g., WiFi and the like), and/or one or more land mobile radio (LMR) protocols (e.g., European Telecommunications Standards Institute Digital Mobile Radio (ETSI-DMR), Terrestrial Trunked Radio (TETRA), APCO Project 25 (P25), Digital Mobile Radio (DMR), and the like), among numerous other examples.
Mobile radios in an infrastructure-based wireless network typically communicate over an air interface with a network-dedicated base station such as a base transceiver station (BTS), an eNodeB, a wireless access point, and/or a WiFi router (among other examples). The base station is generally responsible for relaying communications between mobile radios and/or between other networks (such as the Internet). Direct communication between mobile radios is generally unnecessary (though it is typically still an option) if the mobile radios are within a coverage area of an infrastructure-based wireless network.
An ad-hoc wireless network, in contrast, typically does not include a dedicated base station for relaying communications. Rather, a given mobile radio in an ad-hoc network will typically communicate directly with other mobile radios that may be within the coverage area of the given mobile radio, and may otherwise rely on intermediate mobile radios to relay communication with mobile radios that are outside of the coverage area. Some mobile radios can function (often according to various device modes) in both infrastructure-based wireless networks and ad-hoc wireless networks, as is known to those having skill in the art. An ad-hoc network is often referred to as “direct-mode” network (and is referred to as such in this disclosure).
Given the portable nature of mobile radios (e.g., handheld mobile radios such as smartphones, two-way radios, etc.), the coverage area of a direct-mode network of mobile radios may change as various mobile radios within the network move to different locations. This change in coverage may result in a given mobile radio, having been previously located within the coverage area of a direct-mode network, subsequently being located outside of the coverage area. A mobile radio that is outside the coverage area of the direct-mode network would typically be unable to communicate with other mobile radios within the network (if, for example, the mobile radios are not within a coverage area of an infrastructure-based network).
It is desirable for a public-safety responder to maintain the ability to communicate with other public-safety responders for at least the reason that the immediacy and efficacy with which public-safety responders can communicate with one another are quite often determinative of the ultimate outcome of a given incident. Accordingly, there is a need for methods and systems for presenting an alert when a mobile radio of a public-safety responder is leaving a direct-mode coverage area.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.